1. Field of the Invention
The present invention relates a a system for locating and identifying of defects in metallic materials and in particular in welding seams employing ultrasonic pulse-echo method.
2. Brief Description of the Background of the Invention Including Prior Art
As is known in general only the peak defect signal is employed for evaluating a defect in the ultrasonic flaw detection of welding seams according to the pulse-echo method. However, the result does not coincide with the extent of the damage of the defect as it relates to the final product, in particular in view of interferences there is no one to one correlation between the ultrasonic defect signal and the depth of the defect and therefor, the evaluation of an individual ultrasonic defect signal in this manner is open to serious questions.
For this reason, up to now in general there was required an manual ultrasonic reinspection of suspected defect locations resulting in requirements seriously interfering with a substantially automated production process.
On the other hand there is known a defect size determination, in particular in the evaluation of defects in the ultrasonic testing of sheet metals (J. and H. Krautkramer, Werkstoffprufung mit Ultraschall, Springer-Verlag, Publisher 1975, pages 401 to 415, and Robert C. McMaster, Nondestructing Testing Handbook, New York, 1963 Section 45-24 to 45-26 "Contour of Discontinuities".), where based on the size and frequency of material flaws a quality decision appropriate to the final product can be performed by class comparison according for example to the German delivery standards "Stahl-Eisen-Lieferbedingungen 072" or similarly according to ASTME 435-75 or, respectively ASTME 578-716. In this case there registration of the defects can be provided by recording and the evaluation can be done virtually or by way of a computer. Such a simple determination of the defect surfaces is not possible in the case of welding seams, since in this situation the defects are substantially vertical with respect to the surface of the metal piece and therefor, the usual ultrasonic transmission method cannot be employed.